1. Field of the Invention
The present invention relates to a QoS (Quality of Service) setup technique for a mobile communication, and in particular to a QoS setup method and QoS setup system provided for a mobile node on the move (to be called a MN (mobile node) herein, unless otherwise noted), and a mobile terminal apparatus, home agent and server apparatus used for the aforementioned system.
2. Description of the Related Art
Mobile IP is a protocol (refer to: http://ietf.org.org/internet-drafts/draft-ietf-mip4-rfc3344bis-01.txt) for accomplishing mobility on an IP (Internet protocol) network, and a MN (mobile node) registers with a HA (home agent) a correlation between a HoA (home address) which is assigned permanently and CoA (care of address) which is temporarily utilized at a visiting place. A packet transmitted by a CN (correspondent node), which is an opposite correspondent, to the HoA of a MN is received by a HA as proxy which then tunnels it to the CoA of the MN, thereby enabling the MN to communicate with the CN even at a visiting place.
For mobile IP, a function called route optimization is also defined. Route optimization requires the functions of mobile IP and route optimization not only for the MN and HA, but also for the CN which is an opposite correspondent. The MN registers a CoA not only at the HA but also at the CN which is an opposite correspondent, and the CN tunnels by itself addressed to the CoA of the MN. This causes a packet to transmit itself to the MN via a direct route instead of going by way of the HA.
Incidentally, mobile IP has two protocol definitions, i.e., IP v4 (Internet Protocol version 4; refer to: http://www.ietf.org/rfc/rfc2002.txt) and IP v6 (Internet Protocol version 6; refer to: http://www.ietf.org/rfc/rfc3775.txt), both of which are the same in terms of basic operation. The present invention does not differentiate between mobile IP v4 and mobile IP v6 in the description herein.
In the meantime, a QoS setup has conventionally been carried out for a network applied by a mobile IP as follows. That is, a reservation for a network resource or a request for priority processing at the start of communications to assure characteristics such as band and delay, thereby trying to satisfy a QoS for the communication.
Accordingly, the known protocols for setting such QoS include: RSVP (Resource Reservation Protocol; refer to: http://www.ietf.org/rfc/rfc2205.txt), NSIS (Next Step In Signaling; refer to: http://www.ietf.org/internet-drafts/draft-ietf-nsis-fw-07.txt) (NB NSIS is a framework for signaling which comprises a GIMPS (General Internet Messaging Protocol for Signaling; refer to: http://www.ietf.org/internet-drafts/draft-ietf-nsis-ntlp-04.txt) and NSLP (NSIS Signaling Layer Protocol; (refer to: http://www.ietf.org/internet-drafts/draft-ietf-nsis-qos-nslp-05.txt) for Quality of Service signaling).
For the NSIS specifically, the proposed are not only a method in which a reservation message for a QoS setup follows the same route as data (i.e., On-Path Signaling) but also a method in which a reservation message is sent to a QoS node (i.e., a dedicated server) which then carries out a series of settings for necessary nodes within the network (i.e., Off-Path Signaling).
Meanwhile, prepared as mechanisms for assuring a QoS include packet priority control for a router and MPLS (Multi Protocol LABEL Switching; refer to: http://www.ietf.org/rfc/rfc3031.txt).
The present invention is configured to be usable without specifying any of the above described protocols, signaling methods or assurance mechanisms used for a QoS setup.
FIG. 1 describes a conventional QoS setup method premised on route optimization for a mobile communication system. The mobile communication system shown by FIG. 1 comprises a home network 120 including a mobile node MN 124 and a home agent HA 122, and an IP network 110 including a plurality of routers 142 through 146. Mobile communication between the mobile node MN 124 and a correspondent terminal CN 130 is carried out via a direct route. Note that the description herein is based on the assumption regarding connections, i.e., the CN 130 to a first router 142, the HA 122 to a second router 144, and the MN 124 to a third router 146, respectively.
Meanwhile, FIG. 2 describes a conventional QoS setup sequence for the configuration shown by FIG. 1. Referring to FIGS. 1 and 2, for a mobile node MN 124 with a route optimization function, if the mobile node MN 124 moves away from the home network 120, where it originally belongs, to a zone controlled by the third router 146 located within the IP network 110 through mobile IP (step T1), it first puts a position registration on record at the home agent HA 122 as usual (step T2) In this event, the mobile node MN 124 comes to possess a home address HoA and a care of address CoA according to mobile IP. And the mobile node MN 124 puts a position registration on record at the opposite correspondent terminal CN 130 having a route optimization function in order to carry out a route optimization therewith, and register the care of address CoA (step T3).
The opposite correspondent terminal CN 130 having a route optimization function sends the care of address CoA of the mobile terminal MN 124 having a route optimization function a QoS setup request (step T4). The mobile terminal MN 124 returns a response to the QoS setup request back to the opposite correspondent terminal CN 130 (step T5). As a result, a direct QoS setup is carried out between the mobile terminal MN 124 and opposite correspondent terminal CN 130, thereby establishing a QoS assurance route (step T6).
Such a QoS setup method is disclosed by a patent document 1, et cetera, hence is known to the entity of the present invention as a known technique. In the conventional QoS setup method, however, a QoS is assured for the MN and CN only through the direct route between the aforementioned two nodes and not via the HA, which has created an excessive use of network resources, such as putting a location registration on record at the CN having a route optimization function for the purpose of route optimization every time a MN with a route optimization function changes its location.
But the fact is that the majority of CNs are ordinary terminal with no mobile IP or route optimization functions, which means that most CNs are not capable of storing the CoA of the MN. If a CN is desired to be applicable to mobile IP and route optimization, all the terminals that might possibly become opposite correspondents with the MN must be modified as such, requiring an impractical amount of money and time.
FIG. 3 describes issues in a QoS setup relating to a conventional mobile communication in which route optimization is unavailable. The mobile communication system shown by FIG. 3 comprises a home network 120 including a mobile node MN 126 and a home agent 122, and an IP network 110 including a plurality of routers 142 through 146. And mobile communication between the mobile node 126 and an opposite correspondent terminal CN 132 is available only through a route via the home agent 122. Note that the description herein is based on the assumption regarding connections, i.e., the CN 132 to a first router 142, the home agent HA 122 to a second router 144, and the MN 126 to a third router 146, respectively.
FIG. 4 describes a conventional QoS setup sequence for the system shown by FIG. 3. Referring to FIGS. 3 and 4, a mobile node MN 126 without a route optimization function, if the mobile node MN 126 moves away from the home network 120, where it originally belongs, to a zone watched over by a third router 146 located within the IP network 110 through a mobile IP (step U1), first puts a position registration on record at the home agent HA 122 as usual (step U2). In this event, the mobile node MN 126, even without a route optimization function can possess a home address HoA and a care of address CoA according to the mobile IP, but a mobile node MN 126 without a route optimization function cannot register a care of address CoA at the opposite correspondent terminal CN 132 without a route optimization function.
As the opposite correspondent terminal CN 132 without a route optimization function sends a QoS setup request to the home address HoA of the mobile terminal MN 126, the QoS setup request is received by the home agent HA 122 (step U3). The home agent HA 122 transfers the QoS setup request to mobile terminal MN 125 (step U4) which receives the transferred QoS setup request, returns a response to the QoS request back to the home agent HA 122 (step U5) and further returns a response to the QoS setup request back to the opposite correspondent terminal CN 132 (step U6). As a result, a QoS assurance route is established between the opposite correspondent terminal CN 132 and home agent HA 122 (step U7).
Although the QoS setup method provides a QoS assurance between the CN and HA, there has been an issue of a QoS between the HA and MN not being assured. That is, the route which is set for a QoS is only from the CN 132 to the HoA of the MN 126, leaving the segment between the HoA and CoA at a visiting place of the MN 126 not being set for a QoS conventionally. Note that the situation will be the same if the CN which is an opposite correspondent terminal is a mobile terminal, just like the MN, if the CN which is an opposite correspondent terminal has no route optimization function.
[Patent document 1] Japanese translation of PCT international patent application publication No. 2003-521137